Backlight module

ABSTRACT

A backlight module includes a back plate, a plurality of lamps, a lamp fixing base, and a diffusion plate. The back plate has a cavity. The lamps are disposed on or above the back plate. The lamp fixing base is disposed on the back plate for fixing the lamps. The lamp fixing base has a supporting portion extending along a direction away from the back plate. An orthogonal projection of the supporting portion on the back plate is within a boundary of the cavity. The diffusion plate is disposed above or over the back plate, and the supporting portion is suitable for supporting the diffusion plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 99106292, filed on Mar. 4, 2010. The entirety theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a backlight module. More particularly, theinvention relates to a direct type backlight module.

2. Description of Related Art

In recent years, a liquid crystal display (LCD) gradually replacing acathode ray tube (CRT) display tends to be a mainstream display productin the market. An LCD panel of the LCD is not equipped with a functionof light emission, and therefore a backlight module is required forsupplying a planar light source to the LCD panel and for furtherdisplaying images.

The backlight module can be categorized into a direct type backlightmodule and a side-emitting type backlight module. Generally, the directtype backlight module includes a back plate, a plurality of lamps, and alamp fixing base. The lamps are arranged on the back plate to provide alight source, and the lamp fixing base is assembled to the back platefor holding the lamps. Besides, the backlight module further includes adiffusion plate for diffusing light. The lamp fixing base can have asupporting pillar for supporting the diffusion plate disposed above orover the back plate. When the backlight module withstands an externalforce and encounters vibration or shock, the diffusion plate bears anextremely large instant impact force exerted by the supporting pillar,and the diffusion plate is likely to be collided by the supportingpillar of the lamp fixing base, thus resulting in damages to thediffusion plate.

SUMMARY OF THE INVENTION

The invention is directed to a backlight module which can reduce aninstant impact force exerted on a diffusion plate.

The invention is directed to a backlight module in which a diffusionplate is less likely to be damaged by collision of a supporting pillar.

In the invention, a backlight module including a back plate, a pluralityof lamps, a lamp fixing base, and a diffusion plate is provided. Theback plate has a cavity. The lamps are disposed on or above the backplate. The lamp fixing base is disposed on the back plate for fixing thelamps. The lamp fixing base has a supporting portion extending along adirection away from the back plate. An orthogonal projection of thesupporting portion on the back plate is within a boundary of the cavity.The diffusion plate is disposed above or over the back plate, and thesupporting portion supports the diffusion plate.

According to an embodiment of the invention, the lamp fixing basefurther includes two supporting arms and a plurality of lamp holdersrespectively located on the two supporting arms. The two supporting armsextend from two opposite sides of the supporting portion, and the lampholders are respectively fixed onto the back plate and hang thesupporting portion above the cavity through the two supporting arms.

According to an embodiment of the invention, a width of each of the twosupporting arms is smaller than a width of the cavity.

According to an embodiment of the invention, the supporting portionincludes a first base and a supporting pillar located on the first base,and the first base is connected to the two supporting arms.

According to an embodiment of the invention, a width of the first baseand a width of a bottom of the supporting pillar are both smaller than awidth of the cavity.

According to an embodiment of the invention, a total length of the firstbase and the two supporting arms is greater than a length of the cavity.

According to an embodiment of the invention, a length of a bottom of thesupporting pillar is smaller than a length of the cavity.

According to an embodiment of the invention, one of the lamp holdersincludes a second base, a chuck located on the second base, and apositioning portion disposed opposite to the chuck. The chuck holds oneof the lamps. The back plate further has a plurality of positioningholes, and the positioning portion is lodged in one of the positioningholes.

According to an embodiment of the invention, the backlight modulefurther includes a reflective film disposed on the back plate. Thereflective film has a plurality of slits or an opening corresponding tothe cavity.

According to an embodiment of the invention, a material of the lampfixing base includes a plastic material. Specifically, the plasticmaterial includes polycarbonate (PC), polymethylmethacrylate (PMMA),methyl methacrylate-styrene monomer (MS), polystyrene (PS), and plasticsteel (e.g., polyformaldehyde, POM).

Based on the above, the back plate of the invention has the cavitycorresponding to the supporting portion of the lamp fixing base.Thereby, when the backlight module withstands an external force andencounters vibration or shock, the cavity allows flexible deformation ofthe supporting portion of the lamp fixing base by absorbing the forceexerted on the diffusion plate by the supporting portion. As such, thediffusion plate is less likely to be damaged by collision of thesupporting portion, and the instant impact force exerted on thediffusion plate is reduced.

It is to be understood that both the foregoing general descriptions andthe following detailed embodiments are exemplary and are, together withthe accompanying drawings, intended to provide further explanation oftechnical features and advantages of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a three-dimensional cross-sectional view illustrating abacklight module according to an embodiment of the invention.

FIG. 2 is a three-dimensional cross-sectional view illustrating flexibledeformation of a supporting portion in FIG. 1.

FIG. 3 is a three-dimensional cross-sectional view illustrating thebacklight module depicted in FIG. 1 at another viewing angle.

FIG. 4 is a three-dimensional cross-sectional view illustrating abacklight module according to another embodiment of the invention.

FIG. 5A is a top view illustrating the reflective film depicted in FIG.4.

FIG. 5B is a top view illustrating a reflective film according toanother embodiments of the invention.

FIG. 6 is a schematic top view illustrating the lamp fixing base and theback plate depicted in FIG. 1.

FIG. 7 is a partial three-dimensional view illustrating the back platedepicted in FIG. 4.

FIG. 8 is a partial three-dimensional view illustrating a back plateaccording to another embodiment of the invention.

FIG. 9 is a three-dimensional view of a conventional backlight module.

FIG. 10A illustrates a time-varying impact on a diffusion plate when anexternal force is applied to the backlight module depicted in FIG. 9.

FIG. 10B illustrates a time-varying impact on a diffusion plate when anexternal force is applied to the backlight module depicted in FIG. 1.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a three-dimensional cross-sectional view illustrating abacklight module according to an embodiment of the invention. FIG. 2 isa three-dimensional cross-sectional view illustrating flexibledeformation of a supporting portion in FIG. 1. As shown in FIG. 1, abacklight module 100 of this embodiment includes a back plate 110, aplurality of lamps 120 (two lamps 120 are shown in FIG. 1), a lampfixing base 130, and a diffusion plate 140. The back plate 110 has acavity 112. The lamps 120 are disposed on or above the back plate 110and partially captured within the lamp fixing base 130, and the lampfixing base 130 for fixing the lamps 120 is disposed on the back plate110 as well. The diffusion plate 140 is disposed above or over the backplate 110, the lamps 120, and the lamp fixing base 130.

The lamp fixing base 130 has a supporting portion 132 extending along adirection away from the back plate 110. The supporting portion 132 isused to support or shore up the diffusion plate 140. An orthogonalprojection of the supporting portion 132 on the back plate 110 is withina boundary of the cavity 112, or the orthogonal projection of thesupporting portion 132 corresponds to the cavity 112. The cavity 112allows flexible deformation of the supporting portion 132 within thecavity 112. Thereby, when the backlight module 100 withstands anexternal force and encounters vibration or shock, flexible deformationof the supporting portion 132 occurs at the cavity 112 (as shown in FIG.2), and the cavity 112 allows flexible deformation of the supportingportion 132 caused by the external force exerted on the supportingportion 132. Therefore, the external force is partially or mostlyabsorbed by the flexibly deformed supporting portion 132. As such, thediffusion plate 140 supported by the supporting portion 132 is lesslikely to be damaged by collision of the supporting portion 132 causedby the remaining force. Besides, the instant impact force exerted on thediffusion plate 140 is reduced. On the other hand, the cavity 112 is nota destructive design which may generate holes or openings on the backplate 110. Accordingly, the strength of the back plate 110 remainsunaltered or decreases restrictedly. A material of the back plate 110can be SECC (steel electrically chromate coated) or an aluminum alloyplate (e.g. AL 5052)

Specifically, the lamp fixing base 130 further includes two supportingarms 134 and a plurality of lamp holders 136 respectively located on thetwo supporting arms 134. The two supporting arms 134 extend from twoopposite sides of the supporting portion 132. The lamp holders 136 arerespectively fixed onto the back plate 110 and hang the supportingportion 132 above the cavity 112 through the two supporting arms 134.According to this embodiment, a material of the lamp fixing base 130 is,for example, a plastic material. Particularly, the plastic materialincludes polycarbonate (PC), polymethylmethacrylate (PMMA), methylmethacrylate-styrene monomer (MS), polystyrene (PS), and plastic steel,which should not be construed as a limitation to this invention. Here,the plastic steel specifically refers to a pliable but strong plasticmaterial, e.g. polyformaldehyde (POM). The lamp fixing base 130 in otherembodiments can also be made of other proper materials.

FIG. 3 is a three-dimensional cross-sectional view illustrating thebacklight module depicted in FIG. 1 at another viewing angle. Asindicated in FIG. 3, the supporting portion 132 includes a first base132 a and a supporting pillar 132 b located on the first base 132 a. Thefirst base 132 a is connected to the two supporting arms 134. Thesupporting pillar 132 b extends from the first base 132 a to a directionaway from the back plate 110, and the supporting pillar 132 b is used tohold or support the diffusion plate 140. Besides, each of the lampholders 136 includes a second base 136 a, a chuck 136 b located on thesecond base 136 a, and a positioning portion 136 c disposed opposite tothe chuck 136 b. The chuck 136 b is used to hold or contain the lamps120. The back plate 110 further has a plurality of positioning holes114. The positioning portion 136 c is lodged in one of the positioningholes 114, such that the lamp fixing base 130 is fixed onto the backplate 110.

In FIG. 1, the backlight module 100 of this embodiment may furtherinclude a reflective film 150. The reflective film 150 is disposedbetween the back plate 110 and the lamp fixing base 130 to reflect thelight emitted by the lamps 120. The reflective film 150 has an opening152 (as shown in FIG. 1 and FIG. 2) corresponding to the cavity 112,such that flexible deformation of the supporting portion 132 can occurat the cavity 112. In this embodiment, the opening 152 has a rectangularshape, and the opening 152 can also have a circular or an ellipticalshape, which is not limited in this invention. On the other hand, inorder to enable flexible deformation of the supporting portion 132 orallow the supporting portion 132 to shrink at the cavity 112 when thesupporting portion 132 withstands an external force and encountersvibration or shock, the dimension of the opening 152 can be greater thana dimension of the bottom of the supporting pillar 132 b and evengreater than the dimension of the first base 132 a, which is not limitedin the invention.

Besides, in the embodiment depicted in FIG. 4, the reflective film 150′has a plurality of slits 154 for improving flexibility of the reflectivefilm 150′. As such, flexible deformation of the supporting portion 132is not prevented by the reflective film 150′.

FIG. 5A is a top view illustrating the reflective film depicted in FIG.4. FIG. 5B is a top view illustrating a reflective film according toother embodiment of the invention. The shape of the slits in thereflective film is not limited in this invention. Namely, the slits notonly can have the shape of the slits 154 as shown in FIG. 5A (i.e. theslits 154 are gathered at a region corresponding to the supportingportion 132, so as to allow the flexible deformation of the supportingportion 132 at the cavity 112) but also can have the shape of the slits454 as shown in FIG. 5B or any other appropriate shape (i.e. the slits454 are gathered at an opening corresponding to the supporting portion132, so as to allow the flexible deformation of the supporting portion132 at the cavity 112). In this embodiment as shown in FIG. 5A and FIG.5B, the slits can have a cross shape or a shape of the letter “X”, whilethe number of the slits in other embodiments can be greater than two,which is not limited in this invention.

In the embodiment depicted in FIG. 5A, the slits 154 preferably have aradial shape, which should not be construed as a limitation to theinvention. The center of the radial slits 154 corresponds to thesupporting portion 132 and the cavity 112. The small slits 154 can coverthe back plate 110 to a better extent (particularly cover the cavity112). Hence, light leakage around the supporting portion 132 of thebacklight module 100 can be further reduced.

In the embodiment depicted in FIG. 5B, both the opening and the slitsare formed. The slits 454 have the radial shape, and the center of theradial slits 454 has an opening corresponding to the supporting portion132 and the cavity 112. The smaller or narrower slits 454 can cover theback plate 110 to a better extent, so as to reduce light leakage. On theother hand, the opening 254 enables more flexible deformation of thesupporting portion 132 or allows the supporting portion 132 to shrink atthe cavity 112 when the supporting portion 132 withstands an externalforce and encounters vibration or shock. In this embodiment, the slits454 result in reasonable flexibility of the reflective film, andtherefore the dimension of the opening 254 can be smaller than or equalto the dimension of the bottom of the supporting pillar 132 b or thedimension of the first base 132 a, which should not be construed as alimitation to this invention.

FIG. 6 is a schematic top view illustrating the lamp fixing base and theback plate depicted in FIG. 1. To better illustrate the invention, thechuck 136 b, the positioning portion 136 c, the diffusion plate 140, andthe reflective film 150 depicted in FIG. 1 are not shown in FIG. 6. Withreference to FIG. 6, in this embodiment, a width W1 of each of the twosupporting arms 134 is smaller than a width W2 of the cavity 112, and/ora width W3 of the first base 132 a, a width W4 of a bottom of thesupporting pillar 132 b, and a length L1 of the bottom of the supportingpillar 132 b are smaller than the width W2 of the cavity 112.Accordingly, the supporting portion 132 located at the cavity 112 and aportion of the supporting arms 134 connected to the supporting portion132 are adapted to flexible deformation. In addition, a total length L2of the two supporting arms 134 and the first base 132 a is greater thana length L3 of the cavity 112, such that the supporting portion 132 issuitable for being hung above the cavity 112 by the two supporting arms134. Here, the defined length is parallel to an extending direction ofthe two supporting arms 134 or parallel to an extending direction of oneof the supporting arms 134, and the defined width is perpendicular tothe extending direction of one of the two supporting arms 134. In thisembodiment, the supporting pillar 132 b is a cone column, and thereforethe width W4 of the bottom of the supporting pillar 132 b and the lengthL1 both refer to the diameter of the circular bottom of the cone column,which should not be construed as a limitation to this invention. On theother hand, the first base 132 a, the second base 136 a, and/or the twosupporting arms 134 can have a rectangular shape, a strip shape, or anyother shape.

FIG. 7 is a partial three-dimensional view illustrating the back platedepicted in FIG. 4. FIG. 8 is a partial three-dimensional viewillustrating a back plate according to another embodiment of theinvention. In FIG. 8, the cavity 512 of the back plate 510 is a circularcavity or an elliptical cavity, and the bottom of the cavity 512 canhave various slopes. By contrast, the cavity 212 in FIG. 7 is arectangular cavity or a rounded rectangular cavity, and the cavity 212can have a flat bottom. The cavity formed on the back plate can have anyother appropriate shape in other embodiments that are not depicted inthe drawings, and the bottom of the cavity can also have other shapes,which should not be construed as a limitation to this invention. Thewidth W2 and the length L3 of the cavity 512 both refer to the diameterof the circular cavity 512 according to this embodiment. However,according to another embodiment, given that the cavity 512 has theelliptical shape, the width W2 of the cavity 512 can refer to thecorresponding oval axis (major axis or minor axis), which is not limitedin this invention. In this embodiment, the positioning holes 114 have agourd shape. Wide portions of the positioning holes 114 can be insertedby the positioning portions 136 c of the lamp holders 136, and narrowportions of the positioning holes 114 can be lodged by the positioningportions 136 c for alignment or fixed position. A channel is locatedbetween the wide and the narrow portions, such that the positioningportions 136 c can move back and forth through the channel, which isconducive to assembling and disassembling the lamp holders 136.

FIG. 9 is a three-dimensional view of a conventional backlight module.FIG. 10A illustrates a time-varying impact on a diffusion plate when anexternal force is applied to the backlight module depicted in FIG. 9.FIG. 10B illustrates a time-varying impact on a diffusion plate when anexternal force is applied to the backlight module depicted in FIG. 1. InFIG. 10A and FIG. 10B, the horizontal axis stands for time (unit:second) and the vertical axis stands for the impact force on thediffusion plate (unit: newton). The external force applied to thebacklight module is 10 G/5 ms, for example, wherein G is Newtongravitational constant, i.e. 6.67300×10⁻¹¹ m³ kg⁻¹ s⁻². In FIG. 9, aback plate 610 does not have a cavity corresponding to a supportingportion 632. By contrast, when an external force is applied to thebacklight module 100 depicted in FIG. 1, the cavity 112 corresponding tothe supporting portion 132 allows flexible deformation of the supportingportion 132 of the lamp fixing base 130 by absorbing the force exertedon the diffusion plate 140 by the supporting portion 132. Hence, whenFIG. 10A and FIG. 10B are compared, it can be learned that the maximuminstant impact force on the diffusion plate 140 (shown in FIG. 10B) isapparently less than the maximum instant impact force on the diffusionplate 640 (shown in FIG. 10A) as the same external force 10 G/5 ms isapplied to the backlight module 100 of this embodiment and theconventional backlight module 600 at the time 0.012 S. In the subsequentcomparison of the impact force, the diffusion plate 140 of thisembodiment bears a relatively small impact force, and the deformation ofthe diffusion plate 140 can be mitigated. Namely, the diffusion plate140 is less likely to be damaged.

In light of the foregoing, the back plate of the invention has thecavity corresponding to the supporting portion of the lamp fixing base.Thereby, when the backlight module withstands an external force andencounters vibration or shock, the cavity allows flexible deformation ofthe supporting portion of the lamp fixing base by absorbing the forceexerted on the diffusion plate by the supporting portion. As such, thediffusion plate is less likely to be damaged by collision of thesupporting portion, and the instant impact force exerted on thediffusion plate can be reduced. Moreover, the reflective film disposedbetween the back plate and the lamp fixing base can have the slits orthe opening corresponding to the cavity, such that the supportingportion of the lamp fixing base can successfully have flexibledeformation at the cavity.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of theinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the invention covermodifications and variations of this invention provided they fall withinthe scope of the following claims and their equivalents.

1. A backlight module comprising: a back plate having a cavity; aplurality of lamps disposed above the back plate; a lamp fixing basedisposed on the back plate for fixing the lamps, the lamp fixing basehaving a supporting portion extending along a direction away from theback plate, an orthogonal projection of the supporting portion on theback plate being within a boundary of the cavity; and a diffusion platedisposed over the back plate, the supporting portion being suitable forsupporting the diffusion plate.
 2. The backlight module as claimed inclaim 1, wherein the lamp fixing base further comprising two supportingarms and a plurality of lamp holders respectively located on the twosupporting arms, the two supporting arms extend from two opposite sidesof the supporting portion, and the lamp holders are respectively fixedonto the back plate and hang the supporting portion above the cavitythrough the two supporting arms.
 3. The backlight module as claimed inclaim 2, wherein a width of each of the two supporting arms is smallerthan a width of the cavity.
 4. The backlight module as claimed in claim2, wherein the supporting portion comprises a first base and asupporting pillar located on the first base, and the first base isconnected to the two supporting arms.
 5. The backlight module as claimedin claim 4, wherein a width of the first base and a width of a bottom ofthe supporting pillar are both smaller than a width of the cavity. 6.The backlight module as claimed in claim 4, wherein a total length ofthe first base and the two supporting arms is greater than a length ofthe cavity.
 7. The backlight module as claimed in claim 4, wherein alength of a bottom of the supporting pillar is smaller than a length ofthe cavity.
 8. The backlight module as claimed in claim 2, wherein oneof the lamp holders comprising a second base, a chuck located on thesecond base, and a positioning portion disposed opposite to the chuck,the chuck holds one of the lamps, the back plate further has a pluralityof positioning holes, and the positioning portion is lodged in one ofthe positioning holes.
 9. The backlight module as claimed in claim 1,further comprising a reflective film disposed on the back plate, thereflective film having a plurality of slits or an opening correspondingto the cavity.
 10. The backlight module as claimed in claim 1, wherein amaterial of the lamp fixing base comprises a plastic material includingpolycarbonate, polymethylmethacrylate, methyl methacrylate-styrenemonomer, polystyrene, and polyformaldehyde.
 11. A backlight modulecomprising: a back plate having a cavity; a plurality of lamps disposedabove the back plate; a lamp fixing base disposed on the back plate forfixing the lamps, the lamp fixing base having a supporting portion abovethe cavity, an orthogonal projection of the supporting portion on theback plate being within a boundary of the cavity; and a diffusion platedisposed over the back plate, the supporting portion being suitable forsupporting the diffusion plate.
 12. The backlight module as claimed inclaim 11, wherein the lamp fixing base further comprising two supportingarms and a plurality of lamp holders respectively located on the twosupporting arms, the two supporting arms extend from two opposite sidesof the supporting portion, and the lamp holders are respectively fixedonto the back plate.
 13. The backlight module as claimed in claim 12,wherein a width of each of the two supporting arms is smaller than awidth of the cavity.
 14. The backlight module as claimed in claim 11,further comprising a reflective film disposed on the back plate, thereflective film having a plurality of slits or an opening correspondingto the cavity.
 15. A backlight module comprising: a back plate having acavity; a plurality of lamps disposed above the back plate; a lampfixing base disposed on the back plate for fixing the lamps, the lampfixing base having a supporting portion hung above the cavity and twosupporting arms extend from two opposite sides of the supportingportion, an orthogonal projection of the supporting portion on the backplate being within a boundary of the cavity; and a diffusion platedisposed over the back plate, the supporting portion being suitable forsupporting the diffusion plate; wherein the supporting portion comprisesa first base and a supporting pillar located on the first base, and thefirst base is connected to the two supporting arms.
 16. The backlightmodule as claimed in claim 15, wherein a width of the first base and awidth of a bottom of the supporting pillar are both smaller than a widthof the cavity.
 17. The backlight module as claimed in claim 15, whereina total length of the first base and the two supporting arms is greaterthan a length of the cavity.
 18. The backlight module as claimed inclaim 15, wherein a length of a bottom of the supporting pillar issmaller than a length of the cavity.